This invention relates to printers for printing on media and the media therefor, and more particularly, to a printing system for printing labels at pre-established positions on a continuous strip of media comprising, a strip of media having a printing surface for receiving printed label information, the printing surface having position and/or timing/motion marks thereon along the length thereof associated with pre-defined positions in a manner which does not visually impair subsequent printing on the printing surface; and, a printer for printing on the printing surface, the printer including means for sensing the position and/or timing/motion marks to find pre-defined positions and print lines of data at proper times.
Printing apparatus for printing labels on strip media is known in the art and takes various shapes. A typical prior art printer is depicted in FIG. 1 where it is generally indicated as 10. The printer 10 prints on strip media 12 from the supply roll 14 as it passes over a platen 16 using a printhead 18. The media 12 is moved through the printer 10 by the stepping motor 20 which drives a drive roller 22 while the media 12 is positioned between the drive roller 22 and a pinch roller 24. An encoded wheel 26 is sometimes used to determine the speed or motion of the media 12. If the media 12 is started from a known position, the encoded wheel 26 can also be employed to constantly know the position of the media 12. As depicted in the drawing figure, the encoded wheel 26 can be driven by the motor 20 or from a roller (such as 24) rolling along the media 12. A sensor 28 is employed to read the encoded wheel 26 and provide an electrical signal to computational equipment (not shown) associated with the printer 10. There are numerous problems associated with such an approach, not the least of which is the cost of the computational equipment necessary to do the calculations. If the media 12 is a so-called "linerless" media having adhesive on its reverse surface for direct application to a surface, a release coating is typically applied to the printing surface to keep the media 12 from sticking to itself while in the roll 14. If a roller such as 24 is employed to drive the encoded wheel 26, it may slip on the release coating thereby giving false readings.
As depicted in FIG. 2, the motor 20 does not drive the media 12 at a constant rate. Rather, it moves in a series of steps. As depicted in FIG. 3, this pulling action may result in the creation of standing waves 30 in the media 12 at certain speeds. While shown exaggerated in the drawing figure for ease of understanding, the standing waves 30 can interfere with the quality of the printing on the media 12. Thus, having a source of accurate information on the speed of the media 12 through the printer 10 can be of importance. Since different types and thickness of media 12 will have any standing waves 30 at different speeds, it would be better if the speed information was media-oriented rather than drive motor oriented. Also, if one were to make a printer 10 where the media 12 was not driven by a motor 20 amenable to also driving an encoded wheel 26, having the speed information sourced in the media 12 would be an absolute necessity.
With respect to positional information, that too is best source in the media 12 itself. If one size label is to be printed, it is possible to pre-position the strip of labels in the printer and then keep track of how far the strip has moved. This, of course, requires computational capability once again as well as a memory to maintain the position when the printer is turned off. If there is any slippage, the position information slips as well. Moreover, if a different sized label is used, there must be provision for the user to re-program the printer as to the current printer size. All in all, not a very practical approach.
As depicted in FIG. 4, the media 12 may comprise a plurality of pre-cut labels 32 with no space between them. The prior art typically addresses that by putting positional marks 34 on the media 12 at the start of each label 32 where it does not effect the labels 32 themselves. As shown in FIG. 5, where the pre-cut labels 32 are separated by a gap 36, the marks 34 are not necessary since the edges of the labels 32 can be detected physically by a number of means.
Recently, the linerless media mentioned above has gained great popularity since it does not produce any backing materials that must be disposed of. This is particularly important in automated labeling machines and the like. As depicted in FIG. 6 in simplified form, the media 12 is a strip of paper or such having a surface on the top which accepts the printing ink and adhesive on the opposite or back surface. The media 12 comes off its supply roll 14 and passes under a printhead 38 where the information 40 is printed on it. It then proceeds to a cutter 42 which cuts off the printed label 44. For such a simple application, positional information is unnecessary.
Most companies want their labels to have pre-printed information 46 on them about the sending company, its return address, and the like. Not only does this provide return address information in the event the package is undeliverable as addressed for some reason; but, in addition, it is a form of free advertising as the packages move through the delivery system. As depicted in FIG. 8, the information 40 is intended to be printed in a proper area with relation to the pre-printed information 46 such that a proper label 44 is created when the media is cut on line 48 as in the left side of the drawing figure. In the absence of proper positional information, however, the information 40 may be mis-printed as in the right side of the drawing figure. Thus, for printing on such pre-printed but not pre-cut media, positional information becomes an absolute necessity. One could sense the pre-print 46, but that has certain limitations. Primarily, it would make the position of the pre-print 46 fixed and, quite likely, severely limit the size and style of the pre-print 46. Moreover, there would still be the problem of providing speed/motion information if desired or necessary to the implementation.
Since it is not pre-cut and therefore has no "edges" on the top surface where marks 34 can be made as in FIG. 4, that prior art technique is not available. And, since the back surface is covered with adhesive, it is not practical to put positional or speed/motion marks on the back.
Wherefore, it is an object of the present invention to provide a method and apparatus for marking and sensing positional and/or speed/motion information on linerless media.
It is another object of the present invention to provide a method and apparatus for marking and sensing positional and/or speed/motion information on the printing surface of a linerless media in a manner which does not visually interfere with normal markings thereon.
It is still another object of the present invention to provide a method and apparatus for marking and sensing pre-prints on the printing surface of a linerless media.
It is yet another object of the present invention to provide a method and apparatus for marking and sensing positional information of a linerless media in a manner which does not limit the size, style, or position of pre-prints on the final labels.
It is a further object of the present invention to provide a method and apparatus for marking and sensing speed/motion information on the printing surface of a linerless media in a manner which allows media-dependent information to be provided by the media itself.
It is a still further object of the present invention to provide a method and apparatus for providing and sensing speed/motion information of a linerless media in implementations not employing a drive motor for the media.
Other objects and benefits of this invention will become apparent from the description which follows hereinafter when read in conjunction with the drawing figures which accompany it.